Elastic shaft coupling

ABSTRACT

The invention relates to an elastic shaft coupling, comprising at least one torsion element, with an elastomer body as transfer element, to which connecting flanges are fixed. According to the invention, the axial shortening of the elastomer body, in such an elastic shaft coupling, at high revolutions, can be reduced, without producing the resilience thereof, whereby the elastomer body is encompassed by a circumferential support ring, which is exclusively bonded to the elastomer body.

CROSS REFERENCE TO RELATED APPLICATIONS

Application claim priority under 35 U.S.C. §119 of German ApplicationNo. 199 55 051.4, filed on Nov. 15, 1999. Application also claimpriority under 35 U.S.C. §365 of PCT/EP00/11156, filed ON Nov. 10, 2000.The international application under PCT article 21 (2) was not publishedin English.

BACKGROUND OF THE INVENTION

The invention relates to an elastic shaft coupling comprising at leastone torsion element that, as a transfer element, comprises an elastomerbody, on which connection flanges are secured.

One problem afflicting shaft couplings of the type specified above knownfrom the prior art is the fact that the elastomer body contracts axiallyespecially at higher numbers of revolution. This has to be ascribed tothe fact that the relatively soft elastomer attempts to yield outwardsunder the influence of the centrifugal forces, causing the connectingflanges to be pulled together. This effect is compounded even furtherunder the torsional shearing stress occurring in the transmission of thetorque. This effect is particularly pronounced if the elastomer body ismade of a particularly soft material, or penetrated by coolingapertures. The axial movements of the connection flanges have to becompensated in the adjoining assemblies, which means that substantialexpenditure is required.

It is known according to the prior art (e.g. from DE-C-37 10 390 andDE-A-4 34 722) to interrupt the elastomer body of an elastic shaftcoupling in the center by providing it with ring-shaped disks, which areattached to the coupling by vulcanization and supported on the shaft onthe inside. These ring disks and their support, however, mean thatsubstantial additional expenditure is required, and that the resilienceof the elastic shaft coupling is adversely affected.

It is already known from U.S. Pat. No. 3,910,068 to support theelastomer body of an elastic shaft coupling by means of a cylindricaltube against buckling directed outwards in the radial direction. Theproposed design, however, has a number of drawbacks. The supportingcylindrical tube obstructs the torsional motion and, within theframework of shearing conditioned by torsion, leads to relativemovements between the elastomer body and the rigid cylindrical tube thatcause wear. Furthermore, the support by means of the cylindrical tubeobstructs the dissipation of heat from the elastomer body and results indestruction of the elastomer body by heat when higher outputs need to betransmitted.

Therefore, the problem of the invention is to further develop theelastic shaft coupling of the type specified above to the extent thatthe axial shortening of the elastomer body is reduced while itsresilience is impaired to the least possible extent.

SUMMARY OF THE INVENTION

For solving said problem, the invention proposes that the elastomer bodyis surrounded by a support ring that extends in the circumferentialdirection and is exclusively bonded to the elastomer body and isdesigned in the form of a metal profile comprising on its inner sideprotrusions projecting into the volume of the elastomer body.

The support ring as defined and proposed by the invention, like anexternally applied bandage, holds the elastomer body together andsupports the elastomeric components against the centrifugal force. Theelastomeric compounds of the elastomer body will consequently yieldoutwards to a lesser extent, so that the axial shortening of theelastomer body is avoided to the greatest possible extent, or at leastdecisively reduced. Owing to the fact that the support ring isexclusively supported on the elastomer body, the support ring willhardly impair the resilience of the elastic shaft coupling.

The support ring is preferably mounted in the area located at half ofthe axial length of the elastomer body, i.e. where radial deformation inthe outward direction has to be feared to occur most likely.

The support ring extending in the peripheral direction is usefullyrealized in the form of a metal profile that is provided on its innerside with protrusions projecting into the volume of the elastomer body.The protrusions cause the support ring to attach itself particularlyintimately to the elastomer body and quasi becomes a component of thelatter.

For the purpose of facilitating the assembly and dismantling of theelastic shaft coupling, the elastomer body, like the connection flanges,can be designed in the form of a rotational body divided in segments,whereby the support ring is segmented in the same way and the segmentsof the support ring are provided with connection means for connectingthe segments of the support ring with each other. The connecting meansassure that the segments of the support ring will form a closed ringthat is exclusively supported on the elastomer body, in any after thecoupling has been assembled.

The segments of the support ring usefully comprise fastening eyesprojecting outwards. These fastening eyes are screwed together withconnecting tabs extending in the circumferential direction of theelastomer body. Such a design of the connecting means permitsparticularly simple and quick mounting and removal of the elastomerbody.

So as to avoid excessive heating of the elastomer body, it is providedwith a multitude of cooling air channels. The inlet suction openings ofthe channels, which substantially extend in the axial direction, arearranged in the area of the connection flanges, and the outlet openingsof these channels are substantially arranged in the radial directionalong the periphery of the elastomer body. Such cooling air channelsextending in the axial and radial directions work in a particularlyeffective way to the extent that the rotational motion of the elastomerbody, in a manner that is similar to the operation of a radialcompressor, produce a substantial pressure gradient between the suctioninlet openings and the outlet openings. This pressure gradient providesfor a particularly intensive stream of cooling air flowing through theelastomer body.

An optimal dissipation of the heat is obtained if provision is made fortwo groups of axially and radially extending cooling air channels thatare provided in two axial planes arranged on both sides of the supportring. Owing to the great number of axially and radially extendingcooling air channels located on both sides of the axial center plane, anintensive and uniformly distributed dissipation of the heat is achieved,so that no clusters of heat can develop in the elastomer body.

The two groups of axially and radially extending cooling air channelsare usefully arranged in a symmetrical manner in relation to the axialcenter plane. This creates the same elasticity and heating conditions onboth sides of the support ring on the driving and output sides.Furthermore, the elastomer bodies so designed can be installed duringthe assembly both on the right and left sides.

BRIEF DESCRIPTION OF THE DRAWINGS

An exemplified embodiment of the invention is explained in greaterdetail in the following with the help of the drawing, in which:

FIG. 1 shows a section extending in the axial direction through a shaftcoupling as defined by the invention.

FIG. 2 is a top view A of FIG. 1 developed in the plane of the drawing.

FIG. 3 is an isolated side view of the support ring; and

FIG. 4 is an axial view of the shaft coupling shown in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

The shaft coupling shown in the drawing comprises the two connectionflanges 1 and 2. An elastomer body 3 is arranged between said flanges.The connection flanges 1 and 2 and the elastomer body 3 are bonded toeach other by vulcanization.

In the exemplified embodiment shown, both the connection flanges 1 and 2and the elastomer body 3 are divided in four segments, whereby eachsegment extends over an arc of about 90°.

According to the invention, the elastomer body 3 is surrounded in thearea of half of its axial length by a support ring 4 extending in thecircumferential direction. Said support ring is exclusively supported onthe elastomer body 3. The support ring 4 extending in thecircumferential direction is designed in the form of a metal profilethat is provided in its inner side with the protrusions 5 projectinginwards into the volume of the elastomer body 4. The support ring 4 issegmented in this connection in the same way as the elastomer body 3.The individual segments of the support ring 4 are connected amongthemselves by the connection tabs 6 extending between the individualsupport ring segments in the circumferential direction. The connectiontabs 6 are screwed together with the fastening eyes 7, which are locatedon the outside of the support ring segments and project radially beyondthe outer circumference of the support ring 4. Furthermore, provision ismade in the elastomer body 3 for the cooling air channels 8. Saidcooling air channels 8 have the suction inlet openings 9, whichsubstantially extend axially through the connection flanges 1 and 2, andthe outlet openings 10, which exit substantially radically from theelastomer body 3 on both sides of the support ring 4.

The axially and radially extending cooling air channels 8 aresymmetrically arranged in two axial planes located on both sides of thesupport ring 4 in relation to the axial center plane of the shaftcoupling.

1. An elastic shaft coupling comprising: at least one torsion elementhaving as a transmission element an elastomer body; connection flangessecured on said elastomer body; a support ring (4) extending in acircumferential direction of said elastomer body and surrounding theelastomer body, wherein said support ring is not in contact with theconnection flanges and wherein said support ring is exclusively bondedto the elastomer body (3), and is formed as metal profile having on itsinner side protrusions (5) projecting into the volume of the elastomerbody (3).
 2. The elastic shaft coupling according to claim 1,characterized in that the support ring (4) is arranged in the area ofhalf of the axial length of the elastomer body (3).
 3. The elastic shaftcoupling according to claim 1, characterized in that the elastomer body(3) is designed in the form of a rotational body divided in segments,whereby the support ring (4) is segmented in the same way and thesupport ring segments are provided with connecting means forinterconnecting said segments.
 4. The elastic shaft coupling accordingto claim 3, characterized in that the support ring segments compriseoutwardly projecting fastening eyes (7), the latter being screwedtogether with connection tabs (6) extending in the circumferentialdirection of the elastomer body (3).
 5. The elastic shaft couplingaccording to claim 1, characterized in that the elastomer body (3) isprovided with a multitude of cooling air channels (8), the axiallyextending suction inlet openings (9) of which are arranged in the areaof the connection flanges (1, 2), and substantially radially extendingoutflow openings (10) of which are arranged on the periphery of theelastomer body (3).
 6. The elastic shaft coupling according to claim 5,characterized in that provision is made for two groups of axially andradially extending cooling air channels (8), said channels beingarranged in axial planes arranged on both sides of the support ring (4).7. The elastic shaft coupling according to claim 6, characterized inthat the two groups of axially and radially extending cooling airchannels (8) are symmetrically arranged with respect to the axial centerplane of the shaft coupling.